Process for the preparation of chlorodifluoroamine



3,314,770 PROCESS FOR THE PREPARATION OF CHLORODIFLUOROAMINE William Warren Knipe and Charles Joseph Mackley, Philadelphia, Pa., assignors to Pennsalt Chemicals Corporation, Philadelphia, Pa., a corporation of Pennsylvama No Drawing. Filed June 14, 1963, Ser. No. 287,757 7 Claims. (c1. 23-356) fluoride such as NH F or NH F-HF with chlorine trifi-uoride at a reaction temperature above -40 C. Gaseous chlorine trifluoride reacts smoothly with the ammonium fluoride to yield chlorodifluo-roamine in accord ance with the following equations:

In addition to the above reactions, however, there is albetween the starting reagents to give nitrogen, HF and the following equation:

'the reaction occurring at temperatures between about 50 and 75 C.

In carrying out the process of the invention the equipment used will be inert to the reactants, products and byproducts. Useful materials of construction will be those metals resistant to the eflects of chlorine and HF (eg.

stainless steel, etc.) and also usevinylidene fluoride, copolymers of tetrafluoroethylene and hexafluoropropene, and the like. Other inert materials may also be used, of course, but siliceous materials (e.g. glass, quartz, etc.) are to be avoided because of the attack by HF or chlorine trifluoride that will result.

As indicated, the temperature of the reaction mass will be held between about 50 and 75 C., although it is preferred that the initial temperature of the suspended ammonium fluoride be between about 60 and 73 C. At temperatures below about 50 C. the reaction does not proceed at any practical rate, whereas above about 75 C. exhaustive fluorination of the ammonium fluoride occurs in accordance with Equation above, which, of course, reduces the yield of product.

Gaseous chlorine trifluoride is introduced into the re actor containing the suspension or ammonium fluoride in United States Patent 0 the non-volatile fluorocarbon oil, preferably by leading it through a tube extending below the surface of the The chlorine trifluoride gas may be used tween about 3% and preferably between about 10% and 12%. At a concentration of chlorine trifluoride below about 3%, the localized heating is so small that the reaction requires external heating to bring the temperature to 50 to 75 C. where reaction proceeds at a practical rate. When undiluted chlorine trifluoride is used, however, much external cooling must be employed to control the temperature. The rate at which the chlorine trifluoride-inert gas mixture is introduced into the reaction is not critical and will be adjusted so that the reaction mass temperature will be easily held between about 50 and 75 C., at which temperatures the reaction is carried out, as already indicated.

The non-volatile fluorocarbon oil used for the ammonium fluoride suspension will be a low molecular weight polymer of a highly fluorinated hydrocarbon which is liquid at the reaction temperature and which has no significant vapor pressure at about 75 C. In general these materials are low molecular weight polymers or telomers of fluoroolefins such as those described in US. 3,083,238 and US. 2,875,253. It will be understood the invention is illustrated further by follows:

Example 1 A reactor was constructed of 16 mm. O.D. polychlorotrifluoroethylene polymer (Kel-F) which was compression sealed at both ends with polytetrafluoroethylene (Teflon) plate 0.25 thick. A gas inlet was made from a threaded /8" Kel- F tube led through a drilled and tapped hole in the top Teflon plate and the inlet tube extended below the surface of a suspension of 5 grams of ammonium fluoride (NH F) in 40 ml. of liquid polychlorotrifluoroethylene distilling above C. A gas exit was provided in the equipment by using a 0.25" copper pipe-to-fiare fitting threaded through the Teflon cap. Stirring was accomplished by means of a Teflon coated magnetic bar. The complete reactor was enclosed in an air bath capable of being maintained within :1" C. at temperatures up to 100 C.

A mixture of chlorine trifluoride and nitrogen containing 11.7% by volume of chlorine trifluoride was introduced into the reactor at a gas flow rate of 178 ml. per minute (STP), while the initial suspension temperature was held between 60 and 73 C. The addition took 2.6 hours and a total of 0. 132 mole ClF was introduced. ClF recovered was 6.29 g. (0.068 mole). The reaction proceeded easily, without difiiculty in handling, and the yield of chlorodifluoroarnine obtained was ly above 75 C. exhaustive fluorination of the ammonium fluoride occurred with only a poor yield of chlorodifluo- Instead of using a mixture of chlorine trifluoride and an inert gas, undiluted chlorine trifluoride may be used as in the above example using external cooling to hold the temperature between about 50 and 75 C. whereby similar results are obtained.

It will be understood that numerous changes and varia tions may be made from the above description and ex amples without departing from the spirit and scope of the invention.

We claim:

1. A process for the preparation of chlorodifiuoroamine which comprises reacting chlorine trifiuoride with a suspension of a solid ammonium fluoride in a low molecular weight, fluorocarbon oil having no significant vapor pressure at approximately 75 C. which is selected from the group consisting of polychlorotrifluoroethylenes, telorners from chlorotrifluoroethylene and difluorobromochloromethane, and telomers from peifluoroolefins and perfiuoroalkyl iodides, said chlorine trifluoride being introduced into said oil suspension as a gas admixed with an inert gas diluent, and said reaction being made to occur at a temperature between about 50 and 75 C.

2. The process of claim 1 where the ammonium fluoride is N l-1 F.

3. The process of claim 1 Where the ammonium fluoride is ammonium bifiuoride.

4. The process of claim 1 where the diluent is nitrogen.

5. The process of claim 1 where the diluent is helium.

6. The process of claim 1 where the fluorocarbon oil is a polychlorotrifluoroethylene having no significant vapor pressure at approximately 75 C.

7. The process of claim 1 where the ammonium fluoride is NH F, the fluorocarbon oil is a polychlorotrifluoroethylene having no significant vapor pressure at approximately 75 C, and the inert gas diluent is nitrogen.

References Cited by the Examiner UNITED STATES PATENTS 2,875,253 2/1959 Barnhart 260-653 3,083,238 3/1963 Haupstschein et al. 260-648 3,084,025 4/1963 Gardner et al. 23-14 OTHER REFERENCES OSCAR R. VERTIZ, Primary Examiner. MILTON WEISSMAN, Examiner. 

1. A PROCESS FOR THE PREPARATION OF CHLORODIFULOROAMINE WHICH COMPRISES REACTING CHLORINE TRIFLUORIDE WITH A SUSPENSION OF A SOLID AMMONIUM FLUROIDE IN A LOW MOLECULAR WEIGHT, FLUOROCARBON OIL HAVING NO SIGNIFICANT VAPOR PRESSURE AT APPROXIMATELY 75* C. WHICH IS SELECTED FROM THE GROUP CONSISTING OF POLYCHLOROTRIFLUOROETHYLENES, TELOMERS FROM CHLOROTRIFLUOROETHYLENE AND DIFFLUOROBROMOCHLOROMETHANE, AND TELOMERS FROM PERFLUOROOLEFINS AND PERFLUOROALKYL IODIDES, SAID CHLORINE TRIFLUORIDE BEING INTRODUCED INTO SAID OIL SUSPENSION AS A GAS ADMIXED WITH AN INERT GAS DILUENT, AND SAID REACTION BEING MADE TO OCCUR AT A TEMPERATURE BETWEEN ABOUT 50* AND 75*C. 